The Benefits Trial of PB-04 to Evaluate Safety, PK, and Preliminary Efficacy in Inducing Fetal Globin Expression in Beta Thalassemia Intermedia and Sickle Cell Disease
Bibliographic record
Abstract
Abstract Increased expression of fetal globin (HBG) has been shown to reduce clinical severity of beta-globin disorders and increase survival in sickle cell disease (SCD), through improved globin chain balance in beta thalassemia and reduced HbS polymerization. Pharmacologic approaches are considered most feasible for a majority of patients. Both proportions of F-cells and quantity of hemoglobin F (HbF)/cell are important for therapeutic effects. PB-04 was identified in a high-throughput screen of US and EU-approved drugs to activate HBG gene transcription, without cytotoxicity, to induce fetal globin expression (gamma globin mRNA, F-cells, HbF/cell, HbF), and to suppress or displace 4 repressors of the fetal globin gene promoter (BCL11A, LSD-1, KLF-1, and HDAC-3) in hemoglobinopathy patients' erythroid progenitors. PB-04 enhanced HbF in progenitors from hydroxyurea (HU)-treated patients with sickle cell disease. In in vivo studies, PB-04 induced fetal globin expression >20-fold with oral dosing in anemic baboons, and by 3.5-fold in mice transgenic for 2 copies of the human β-globin gene locus. This agent has been approved and in broad use for Parkinson's Disease treatment for 5 decades in Europe and Canada, to enhance the PK of an active Parkinson's agent, solely in a combination formulation. Because of its safety with chronic dosing up to 1300 mg/day, PB-04 is therefore of interest for repurposing in the treatment of thalassemia and SCD. This Ph1b trial (NCT004432623) will evaluate safety, tolerability, PK, and preliminary efficacy (fetal globin expression) with at least 3 escalating dose cohorts in up to 24 beta thalassemia intermedia (BTI) patients and 12 patients with sickle cell disease, > 18 years, both genders, with 12 weeks of treatment and 4 weeks of follow-up. Doses to be explored were selected from safe and active human equivalent doses in preclinical toxicology and efficacy studies in 2 species. Primary inclusion criteria include clinical diagnosis of BTI, including HbE beta thalassemia, with at least one beta globin gene mutation, or diagnosis of HbSS or HbSb thalassemia (after dose selection); total Hb levels 6-10 gm/dL. Exclusion criteria include red blood cell (RBC) transfusion within 2 months prior to administration of study medication, receiving regular transfusions, and hepatic or renal function > 3 x institutional ULN. Primary endpoints include occurrence, severity, and duration of adverse events by CTCAE v5.0 criteria and PK parameters. Secondary endpoints include change from baseline in assays of HbF expression, total Hb, markers of hemolysis . Exploratory endpoints include select polymorphisms associated with basal fetal globin expression and in vitro responses to the study drug. Statistical analysis will assess the rate of adverse events, PK parameters by dose, and changes in F-cells, F-reticulocytes, HbF/cell, HbF (% and total), compared to 2 averaged baseline values using the Wilcoxon signed rank test. Changes will be analyzed by mixed effect models during the 12-week dosing and 4-week follow-up period. Currently 3 dose cohorts with BTI are enrolled. This study, if successful, will provide a rational basis for definitive trials of an established safe oral therapeutic, with no overlapping toxicities with other experimental or approved agents, for combined use with HU and other therapeutics which enhance red cell viability in the globin disorders. The expertise and contributions of Jim Cradock of NCATS TRND to this work before his passing are gratefully acknowledged. Disclosures Kuo: Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Apellis: Consultancy; Bluebird Bio: Consultancy; Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Honoraria; Alexion: Consultancy, Honoraria. Sheth: CRISPR: Consultancy; Bluebird bio: Consultancy; Bristol Myers Squibb: Consultancy, Research Funding; Chiesi: Consultancy; Imara: Research Funding; Agios: Consultancy; Dispersol: Research Funding. Al-Samkari: Moderna: Consultancy; Amgen: Research Funding; Rigel: Consultancy; Argenx: Consultancy; Novartis: Consultancy; Dova/Sobi: Consultancy, Research Funding; Agios: Consultancy, Research Funding. Pace: Imara Inc.: Consultancy. Kuypers: Forma Therapeutics, Inc.: Research Funding. Nouraie: Phoenicia BioScience Inc.: Consultancy. Perrine: Agios Pharmaceuticals: Consultancy; Emmaus Medical: Consultancy.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".